 Okay, let's go ahead and write this reaction for the alpha-promination of carboxylic acids. Of course, it's the Hel-Bolhard-Zalinsky reaction. We already talked about the products that you would get from this reaction. And remember, we know these two reactions separately already, okay? So, we know how to convert acid chloride to acid bromide using PBR3. And we know that if we deprotonated the alpha proton here, we could make the alpha bromide there. But we have to make the actual acyl bromide before we can deprotonate that alpha proton because this proton here is more acidic than the alpha proton, okay? So, we got to watch out about that, okay? And then, of course, this second step is just to hydrolyze the acyl bromide that you had made before, okay? So, has everybody gotten what's written down what I have here? You got it, Vanira? So, let's do the mechanism now. So, the first thing you're going to do is react with phosphorus tribromide, your carboxylic acid. Okay, remember, this is the more nucleophilic of the two oxygens, so you can think of those electrons donating in and then attacking like that. You lose your one-air bromine set. This bromine is going to attack the electrophilic carbonyl carbon there. You can see it's a superelectrophile. It's been protonated already. Okay, now we're going to have these electrons come back down and kick off the good leading group with a better leading group, is this one here? Like that? Being the base that you propane. So, remember, the first thing we make, the intermediate, is the acid bromide. So, there's going to be some base in here. It's going to want to remove, so now these are the most acidic hydrogens, right? So, now some base in here is going to remove that hydrogen. So, what we're doing is to tamarizing, okay? HB plus, we've done so far. This is going to do this. Now, we're going to make, that's going to be the enol. We've done so far. Okay, wonderful. And so, BR2 in there as well. Remember that? So, what's going to happen now? Remember, the alpha carbon is nucleophilic. Y'all remember that? Okay? So, what's going to happen is these electrons are going to come down and kind of promote that nucleophilicity of that carbon, okay? So, when that happens, these electrons are going to attack the bromine there. We get alpha bromination, BR minus. So, one of these BR minuses might have been our bases before, okay? So, we can think of that BR minus removing that from the top like that. Can I erase the top? Does everybody got everything on the top? I'm going to erase that. This would be our product if we didn't do the second step. Does everybody understand what I'm saying? Yeah. So, the second step, we're adding a nucleophile, which is water. The water is going to react with that carbonyl carbon, because this is an acid bromide very quickly. Attack there, up like that. We should put, this is the same thing with this one. So, this one is going to come down. You'll lose the good lead group, as you would imagine you did. I'm going to erase this part of the bottom, because everybody got in that part. And once it's going to happen, we could have put whatever base, but let's just use this as our base. It's going to deprotonate the protonated carboxylic acid. And we're going to show our product. Tubromohexanoic acid. Or heptanoic acid, sorry. Any questions on it? Questions on the mechanism? Okay.